pussuw commented on code in PR #16499:
URL: https://github.com/apache/nuttx/pull/16499#discussion_r2135747383
##########
fs/vfs/fs_fcntl.c:
##########
@@ -347,23 +282,95 @@ int fcntl(int fd, int cmd, ...)
va_start(ap, cmd);
- /* Get the file structure corresponding to the file descriptor. */
-
- ret = file_get(fd, &filep);
- if (ret >= 0)
+ switch (cmd)
{
- /* Let file_vfcntl() do the real work. The errno is not set on
- * failures.
- */
+ case F_DUPFD:
+ /* Return a new file descriptor which shall be the lowest numbered
+ * available (that is, not already open) file descriptor greater than
+ * or equal to the third argument, arg, taken as an integer of type
+ * int. The new file descriptor shall refer to the same open file
+ * description as the original file descriptor, and shall share any
+ * locks. The FD_CLOEXEC flag associated with the new file
+ * descriptor shall be cleared to keep the file open across calls to
+ * one of the exec functions.
+ */
- ret = file_vfcntl(filep, cmd, ap);
- file_put(filep);
- }
+ {
+ ret = dup3(fd, va_arg(ap, int), 0);
Review Comment:
This is wrong, the argument is the smallest fd number requested, NOT the
exact fd number:
F_DUPFD (int)
Duplicate the file descriptor fd using the lowest-numbered
available file descriptor greater than or equal to arg.
This is different from dup2 which uses exactly the file
descriptor specified.
How I wrote it was correct.
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